Balance charging the 8-cell LiFePO4 battery pack using the Turnigy Accucell 8150 balance charger.
By Julian
Youtuber, shed dweller, solar charge controller aficionado
Good morning all…
Youtuber, shed dweller, solar charge controller aficionado
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That device will unbalance your pack – bin it
When they get down to 2,5V often!
A fully charged LifePo4 cell is only 3.6v?
one note is that those battery monitors aren't exactly accurate. it's typical for them to be out about +- 0.05V on the per cell voltage. perfectly fine for monitoring when your batteries are dead, but they will typically show a perfectly balanced pack as being imbalanced.
You need to toss the Battery Murdering System.
Have you thought about using an adc like ads1115 and a small arduino to use as a cell monitor that can provide warning and battery protection? I am not near as skilled in EE as you and have put one together to manage a 4 cell lifepo pack and it is essentially as accurate as my Fluke 87… I was very pleasantly surprised. The 1115 on a breakout board like the adafruit example makes it very easy, uses I2c, ready to go!
balancing takes ages. i have waited hours for cells that are 300mV low to catch up.
If you want to balance the battery a bit quicker you can use your charger in 1S mode at approx 1.5A and charge each individual cell through the balance port.
Ie. Connect Charger + – to Balance port 1 and 2 charge at no more than 1.5A. then port 2 and 3 etc. (You can make up a cable with 2 pins to go to your chargers +-)
Using the chargers resistors to accomplish a balance takes way longer than doing each cell individually at 1.5A.
I would suggest keeping an eye on the balance port wires the first time you try this as the wires are thin and might get hot. If this is the case drop you charge rate to 1.4A and check if temps are any better. Once you get a good Rate make a note for future charges via balance port.
This method works nice and quick for a battery that is way unbalanced like yours.
fyi minimum lifepo4 voltage is 2v under load, bms's are designed to cut off at this point and return when voltage recovers, so if you cut out you can always limp home, though i wouldnt recommend limping too far
I love these Lipo checkers too but these drain power from first cell, so they are like unbalancers too. And basic rule is that each wire has to be fused. I always separately fuse all my balance wires (closest to battery terminals). So no risk of FIRE.
Love your videos btw.
great work 🙂 I don't think you need to be too concerned about the load voltage of the cells, voltage will naturally dip when drawing large currents which they are more than happy to do
I often find that with these meters that they are so inaccurate. The best one I have used is the hobbyking battery medic system which can balance cells for you too.
I deal with batteries every day and you want to monitor the temps during charging. Saw the cut off at 80c. If you can, add thermal sensing. Thermal runaway is scary.